Deadly massacre adds 17 names to list of lives lost in 20 years of school shootings in America

The deadly massacre at Marjory Stoneman Douglas High School in Parkland, Fla., added 17 names to the list of lives claimed in school shootings in America.

For twenty years, presidents have addressed the American people in the wake of massacres at schools in the United States, from the 1999 massacre at Columbine High School in Columbine, Co., to the mass shooting in Parkland, Florida on Feb. 14.